This invention concerns wheeled carriers for hand luggage and the like which are foldable for convenient storage and transportation when not in use.
The invention relates more particularly to luggage carriers, or caddies, of the general type which includes a flat elongated bed frame with a handle at one end and with a relatively short platform projecting at right angles at the other end. A pair of wheels are journaled on a wheel axis adjacent the intersection of the platform and frame. The bed frame is typically formed in two sections which can be folded into nesting relation, and the platform is foldable into coplanar relation with the main frame.
Such luggage caddies are commonly made of wire or light tubing and are intended to carry only relatively light loads, such as one or two suitcases of moderate size. Luggage caddies of that general type are described, for example, in U.S. Pat. No. 3,947,054 to Herbert Charles Hall and patent 4,062,565 to Gilbert J. Holtz.
An important object of the present invention is to provide a luggage caddy that is capable of handling relatively heavy and bulky loads, while retaining substantially the same convenience of manipulation and without significantly increasing the weight of the caddy itself.
The present applicants have found that a critical problem in such luggage caddies is the provision of sufficient strength in the relatively long bed frame, especially at the hinge coupling between its two frame sections. That hinge must be positively lockable in operating position with the two frame sections extending in a common plane. Moreover, the locking mechanism must be able to resist significant torques in both directions about the hinge axis.
In loading position of the caddy the bed frame is typically vertical, with the horizontal platform supported on a ground-engaging foot at its outer edge and by the caddy wheels. The luggage is typically loaded onto the horizontal platform with an edge of each piece of luggage contacting the forward face of the bed frame. The loaded caddy is rotated into traveling position by pulling the handle back, swinging the entire caddy about the wheel axis and lifting the platform clear of the ground. As the platform foot first leaves the ground, that action subjects the hinge lock to strong bending stress in a rearward direction.
In normal traveling position of the caddy the load is typically substantially balanced on the wheels, so that relatively little weight needs to be supported by the handle. However, in maneuvering the caddy the handle is occasionally lowered nearly to the ground. The bed frame then acts as a load-carrying beam supported by the handle at one end and by the wheels at the other end. The hinge lock is then subject to strong bending stress in a forward direction. Thus, the bed frame must have sufficient longitudinal stiffness, and the hinge lock must provide positive and fully reliable definition in both angular directions about the hinge axis. The present invention aims to provide improved frame and lock structure for meeting those conditions.
A further aspect of the present invention provides a luggage caddy that is capable of standing by itself with its bed frame vertical, both in loading position and with its platform and upper frame section folded.
The weight and the cost of fabrication of the present luggage caddy are minimized by designing many of the individual members or sections to perform more than one function. The number of parts and their total weight are thereby reduced.
Thus, for example, foot formations incorporated in the main lower frame structure not only hold the caddy in loading position, but also engage truss structure on the foldable platform, supporting the latter when the caddy is tipped rearwardly into traveling position.
Also, the truss-like structure of the upper frame is directly utilized to provide opposing abutments for the locking mechanism by which the two frame sections are positively but releasably locked in operating position. That lock mechanism is operated by relative compression of the resilient side members of the upper frame, somewhat as in the above identified patent to Holtz but without the duplication of cross members required in the Holtz structure and without exposing sharp hook formations when the frame is folded. Also, the present preferred structure facilitates operation of the lock by smoothly tapering the side members of the upper frame.